The invention relates to a process for the production of alkoxytetrabromoctanes.
Unsaturated aliphatic and/or cycloaliphatic compounds normally are brominated by the addition of bromine to the double bond at low temperatures. Due to possible side reactions, such as, for example, the splitting off of hydrogen bromide, as well as the formation of higher brominated products, the bromination is almost always conducted in inert solvents. Especially suitable as inert solvents serving as diluents for the unsaturated compounds, for facilitating the removal of the heat of reaction and for reducing the formation of by-products are halogenated hydrocarbons, e.g., chloroform, methylene chloride, fluorochlorinated hydrocarbon, petroleum ether, ether, carbon disulfide and acetic acid. However, the reaction mixtures thus-produced during the bromination of alkyl octadienyl ethers have the serious disadvantage that they are discolored even at room temperature and, after separation of the solvent, only highly discolored products can be obtained. These highly discolored products can be purified by distillation under a high vacuum but associated with this purification operation is a rather large loss in the yield. Also, technically expensive devices are necessary and render the products, which are used as intermediates for the chemical industry, as well as flame retardants in thermoplastics, especially in expandable styrene polymers, substantially more expensive.
The reaction known as hydroxybromination of unsaturated compounds with bromine in water or with mixtures of bromine and water produces, depending on the reaction conditions, predominately or exclusively bromohydrins by the simultaneous chemical addition of a bromine cation and a hydroxy group to the double bond. See Houben-Weyl, "Methoden der organischen Chemie" V/4: 133-139, Stuttgart 1960. Additional examples of a hydrobromination can be found in German Unexamined Laid-Open Application DOS No. 1,804,804, Examples 1-4. Thus, it is possible to introduce only half of the bromine atoms into the compound possible with organic solvent bromination and an entirely different class of compounds is produced.
It is an object of this invention to provide a process for the production of alkoxytetrabromoctanes in the pure form, without appreciable proportions of colored impurities, with only minor technical and apparatus expenditures.